Have you read either of these articles:
This should give some insight into bank shutdowns. Seems the federal government is putting pressure on banks to understand the source of funds. Depositing a lot of cash in a really short timeframe triggers some red flags. While this hobby isn't Factoring, and isn't illegal, it looks a lot like suspicious activity from a bank point of view, and we've probably all got a lot of SARs filed against us over the years.